Clock signal generator
First Claim
1. A clock signal generator, comprising:
- a clock generator having at least a first multiplier, which has a first variable multiplying factor, for multiplying an input reference clock signal by the first variable multiplying factor to generate a first clock signal of a first frequency and a second multiplier, which has a second variable multiplying factor, for multiplying the input reference clock signal by the second variable multiplying factor to generate a second clock signal of a second frequency;
a clock selector for receiving a status signal specifying a desired clock frequency for a functional block, for supplying the functional block with the first clock signal when the desired frequency equals the first frequency, and for supplying the functional block with the second clock signal when the desired frequency equals the second frequency, and for supplying the clock generator with an operation control signal, said operation control signal for stopping the first multiplier when the desired frequency is the second frequency and for stopping the second multiplier when the desired frequency is the first frequency.
1 Assignment
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Accused Products
Abstract
A clock signal generator can prevent unnecessary power consumption and can lower the power consumption of a system or a chip as a whole. A clock generator has a plurality of multipliers having variable multiplying factors and multiplying a single input reference clock signal by a designated multiplying factor. A plurality of frequency dividers have variable divide factors and divide a clock signal by a designated dividing factor. A clock selector selects a clock signal which has a required frequency according to a status signal STS from each of the functional locks from among the clock signals having a plurality of frequencies generated by the clock generator. The clock selectors stops the operation of the multipliers or the frequency dividers which are generating unused frequencies by switching clock signals.
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Citations
15 Claims
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1. A clock signal generator, comprising:
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a clock generator having at least a first multiplier, which has a first variable multiplying factor, for multiplying an input reference clock signal by the first variable multiplying factor to generate a first clock signal of a first frequency and a second multiplier, which has a second variable multiplying factor, for multiplying the input reference clock signal by the second variable multiplying factor to generate a second clock signal of a second frequency; a clock selector for receiving a status signal specifying a desired clock frequency for a functional block, for supplying the functional block with the first clock signal when the desired frequency equals the first frequency, and for supplying the functional block with the second clock signal when the desired frequency equals the second frequency, and for supplying the clock generator with an operation control signal, said operation control signal for stopping the first multiplier when the desired frequency is the second frequency and for stopping the second multiplier when the desired frequency is the first frequency. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9)
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2. A clock signal generator, comprising:
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a clock generator having at least one multiplier, which has a variable multiplying factor, for multiplying an input reference clock signal by a designated multiplying factor and at least one frequency divider, which has a variable dividing factor, for dividing the input reference clock signal by a designated dividing factor; a clock selector for selecting a desired clock signal having a desired frequency from outputs of the at least one multiplier and the at least one divider and for supplying the desired clock signal to a functional block, the clock selector receiving a status signal from the functional block which specifies the desired frequency; wherein said multiplier comprises; a first pulse signal generator receiving the input reference clock signal and generating a first pulse signal which has a predetermined pulse width according to the input reference clock signal; a decision circuit specifying a delay value according to a first natural number, the first natural number determining the designated multiplying factor; a delay circuit delaying the first pulse signal according to the delay value to form a delayed pulse signal; an output circuit switching an output level between a first level and a second level at each input of the first pulse signal or a second pulse signal; a second pulse signal generator receiving the delayed pulse signal from the delay circuit and generating the second pulse signal and a third pulse signal which have a complementary relationship with each other, the second pulse signal generator generating the second and third pulse signals using the first natural number designating the multiplying factor and supplying the second pulse signal to the delay circuit and the output circuit; and a pulse phase adjusting circuit comparing the first pulse signal generated by the first pulse signal generator with the third pulse signal and feeding back a result of the comparison to the delay circuit to adjust a phase of the delayed pulse signal.
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10. A clock signal generator, comprising:
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a clock generator having a plurality of multipliers, each having a variable multiplying factor, for multiplying an input reference clock signal by designated multiplying factors and a plurality of frequency dividers, each having a variable dividing factor, for dividing the input reference clock signal by designated dividing factors; a clock selector for selecting desired clock signals having desired frequencies from outputs of the multipliers and dividers and for supplying the desired clock signals to a plurality of functional blocks, the clock selector receiving status signals from the functional blocks which specify the desired frequencies; wherein the clock selector includes a clock selecting circuit for receiving the status signals and for generating operation control signals, said operation control signals supplied to the plurality of multipliers and the plurality of dividers and are for enabling the multipliers and dividers which generate any one of the desired clock signals and for stopping the multipliers and dividers that do not generate any one of the desired clock signals. - View Dependent Claims (11, 12, 13, 14, 15)
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Specification